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Commit f4f52092 authored by Sven Marcus's avatar Sven Marcus
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Python bindings integration

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# build directories # build directories
build/ build/
bin/ bin/
cmake-build-debug/
MSVC2017/ MSVC2017/
VS2017/ VS2017/
# Python
_skbuild/
dist/
*.egg-info/
__pycache__/
.venv/
# IDE # IDE
.vscode/ .vscode/
.sync/ .sync/
.idea/ .idea/
# Simulation results
output/
# MacOS # MacOS
.DS_Store .DS_Store
image: irmb/virtualfluids-deps:latest image: irmb/virtualfluids-python-deps
stages: stages:
- build - build
...@@ -7,25 +7,49 @@ stages: ...@@ -7,25 +7,49 @@ stages:
build: build:
stage: build stage: build
cache:
key: "$CI_JOB_NAME-$CI_COMMIT_REF_SLUG"
paths:
- _skbuild
artifacts: artifacts:
paths: paths:
- build/ - _skbuild/
- Python/venv
before_script:
- python3 -m venv --system-site-packages Python/venv
- source Python/venv/bin/activate
script:
- python3 setup.py install
virtual_fluids_basics_test:
stage: test
before_script: before_script:
- export DEBIAN_FRONTEND=noninteractive - export VF_UNITTESTS=$(find _skbuild -name basicsTests)
- apt-get update
script: script:
- cmake -S . -B build -DBUILD_VF_CPU:BOOL=ON -DBUILD_VF_UNIT_TESTS:BOOL=ON - $VF_UNITTESTS
- cmake --build build --target VirtualFluidsCore
- cmake --build build --target basicsTests
test: test_python_bindings:
stage: test stage: test
artifacts:
when: on_failure
paths:
- output/mq/mq10000/
before_script: before_script:
- export DEBIAN_FRONTEND=noninteractive - export PYTHONPATH="Python"
- source Python/venv/bin/activate
script: script:
- build/bin/basicsTests - python3 Python/test_geometry.py
\ No newline at end of file - python3 Python/test_boundaryconditions.py
- python3 Python/test_kernel.py
- python3 Python/test_muparser.py
- python3 -m unittest Python/test_poiseuille_l2.py
\ No newline at end of file
version: 1.0.{build}
image:
- Visual Studio 2017
- Visual Studio 2015
test: off
skip_branch_with_pr: true
build:
parallel: true
platform:
- x64
- x86
environment:
matrix:
- PYTHON: 36
CPP: 14
CONFIG: Debug
- PYTHON: 27
CPP: 14
CONFIG: Debug
- CONDA: 36
CPP: latest
CONFIG: Release
matrix:
exclude:
- image: Visual Studio 2015
platform: x86
- image: Visual Studio 2015
CPP: latest
- image: Visual Studio 2017
CPP: latest
platform: x86
install:
- ps: |
if ($env:PLATFORM -eq "x64") { $env:CMAKE_ARCH = "x64" }
if ($env:APPVEYOR_JOB_NAME -like "*Visual Studio 2017*") {
$env:CMAKE_GENERATOR = "Visual Studio 15 2017"
$env:CMAKE_INCLUDE_PATH = "C:\Libraries\boost_1_64_0"
$env:CXXFLAGS = "-permissive-"
} else {
$env:CMAKE_GENERATOR = "Visual Studio 14 2015"
}
if ($env:PYTHON) {
if ($env:PLATFORM -eq "x64") { $env:PYTHON = "$env:PYTHON-x64" }
$env:PATH = "C:\Python$env:PYTHON\;C:\Python$env:PYTHON\Scripts\;$env:PATH"
python -W ignore -m pip install --upgrade pip wheel
python -W ignore -m pip install pytest numpy --no-warn-script-location
} elseif ($env:CONDA) {
if ($env:CONDA -eq "27") { $env:CONDA = "" }
if ($env:PLATFORM -eq "x64") { $env:CONDA = "$env:CONDA-x64" }
$env:PATH = "C:\Miniconda$env:CONDA\;C:\Miniconda$env:CONDA\Scripts\;$env:PATH"
$env:PYTHONHOME = "C:\Miniconda$env:CONDA"
conda --version
conda install -y -q pytest numpy scipy
}
- ps: |
Start-FileDownload 'http://bitbucket.org/eigen/eigen/get/3.3.3.zip'
7z x 3.3.3.zip -y > $null
$env:CMAKE_INCLUDE_PATH = "eigen-eigen-67e894c6cd8f;$env:CMAKE_INCLUDE_PATH"
build_script:
- cmake -G "%CMAKE_GENERATOR%" -A "%CMAKE_ARCH%"
-DPYBIND11_CPP_STANDARD=/std:c++%CPP%
-DPYBIND11_WERROR=ON
-DDOWNLOAD_CATCH=ON
-DCMAKE_SUPPRESS_REGENERATION=1
.
- set MSBuildLogger="C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
- cmake --build . --config %CONFIG% --target pytest -- /m /v:m /logger:%MSBuildLogger%
- cmake --build . --config %CONFIG% --target cpptest -- /m /v:m /logger:%MSBuildLogger%
- if "%CPP%"=="latest" (cmake --build . --config %CONFIG% --target test_cmake_build -- /m /v:m /logger:%MSBuildLogger%)
on_failure: if exist "tests\test_cmake_build" type tests\test_cmake_build\*.log*
CMakeCache.txt
CMakeFiles
Makefile
cmake_install.cmake
.DS_Store
*.so
*.pyd
*.dll
*.sln
*.sdf
*.opensdf
*.vcxproj
*.filters
example.dir
Win32
x64
Release
Debug
.vs
CTestTestfile.cmake
Testing
autogen
MANIFEST
/.ninja_*
/*.ninja
/docs/.build
*.py[co]
*.egg-info
*~
.*.swp
.DS_Store
/dist
/build
/cmake/
.cache/
sosize-*.txt
pybind11Config*.cmake
pybind11Targets.cmake
[submodule "tools/clang"]
path = tools/clang
url = ../../wjakob/clang-cindex-python3
python:
version: 3
requirements_file: docs/requirements.txt
language: cpp
matrix:
include:
# This config does a few things:
# - Checks C++ and Python code styles (check-style.sh and flake8).
# - Makes sure sphinx can build the docs without any errors or warnings.
# - Tests setup.py sdist and install (all header files should be present).
# - Makes sure that everything still works without optional deps (numpy/scipy/eigen) and
# also tests the automatic discovery functions in CMake (Python version, C++ standard).
- os: linux
dist: xenial # Necessary to run doxygen 1.8.15
name: Style, docs, and pip
cache: false
before_install:
- pyenv global $(pyenv whence 2to3) # activate all python versions
- PY_CMD=python3
- $PY_CMD -m pip install --user --upgrade pip wheel setuptools
install:
# breathe 4.14 doesn't work with bit fields. See https://github.com/michaeljones/breathe/issues/462
- $PY_CMD -m pip install --user --upgrade sphinx sphinx_rtd_theme breathe==4.13.1 flake8 pep8-naming pytest
- curl -fsSL https://sourceforge.net/projects/doxygen/files/rel-1.8.15/doxygen-1.8.15.linux.bin.tar.gz/download | tar xz
- export PATH="$PWD/doxygen-1.8.15/bin:$PATH"
script:
- tools/check-style.sh
- flake8
- $PY_CMD -m sphinx -W -b html docs docs/.build
- |
# Make sure setup.py distributes and installs all the headers
$PY_CMD setup.py sdist
$PY_CMD -m pip install --user -U ./dist/*
installed=$($PY_CMD -c "import pybind11; print(pybind11.get_include(True) + '/pybind11')")
diff -rq $installed ./include/pybind11
- |
# Barebones build
cmake -DCMAKE_BUILD_TYPE=Debug -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -DPYTHON_EXECUTABLE=$(which $PY_CMD) .
make pytest -j 2 && make cpptest -j 2
# The following are regular test configurations, including optional dependencies.
# With regard to each other they differ in Python version, C++ standard and compiler.
- os: linux
dist: trusty
name: Python 2.7, c++11, gcc 4.8
env: PYTHON=2.7 CPP=11 GCC=4.8
addons:
apt:
packages:
- cmake=2.\*
- cmake-data=2.\*
- os: linux
dist: trusty
name: Python 3.6, c++11, gcc 4.8
env: PYTHON=3.6 CPP=11 GCC=4.8
addons:
apt:
sources:
- deadsnakes
packages:
- python3.6-dev
- python3.6-venv
- cmake=2.\*
- cmake-data=2.\*
- os: linux
dist: trusty
env: PYTHON=2.7 CPP=14 GCC=6 CMAKE=1
name: Python 2.7, c++14, gcc 6, CMake test
addons:
apt:
sources:
- ubuntu-toolchain-r-test
packages:
- g++-6
- os: linux
dist: trusty
name: Python 3.5, c++14, gcc 6, Debug build
# N.B. `ensurepip` could be installed transitively by `python3.5-venv`, but
# seems to have apt conflicts (at least for Trusty). Use Docker instead.
services: docker
env: DOCKER=debian:stretch PYTHON=3.5 CPP=14 GCC=6 DEBUG=1
- os: linux
dist: xenial
env: PYTHON=3.6 CPP=17 GCC=7
name: Python 3.6, c++17, gcc 7
addons:
apt:
sources:
- deadsnakes
- ubuntu-toolchain-r-test
packages:
- g++-7
- python3.6-dev
- python3.6-venv
- os: linux
dist: xenial
env: PYTHON=3.6 CPP=17 CLANG=7
name: Python 3.6, c++17, Clang 7
addons:
apt:
sources:
- deadsnakes
- llvm-toolchain-xenial-7
packages:
- python3.6-dev
- python3.6-venv
- clang-7
- libclang-7-dev
- llvm-7-dev
- lld-7
- libc++-7-dev
- libc++abi-7-dev # Why is this necessary???
- os: linux
dist: xenial
env: PYTHON=3.8 CPP=17 GCC=7
name: Python 3.8, c++17, gcc 7 (w/o numpy/scipy) # TODO: update build name when the numpy/scipy wheels become available
addons:
apt:
sources:
- deadsnakes
- ubuntu-toolchain-r-test
packages:
- g++-7
- python3.8-dev
- python3.8-venv
# Currently there is no numpy/scipy wheels available for python3.8
# TODO: remove next before_install, install and script clause when the wheels become available
before_install:
- pyenv global $(pyenv whence 2to3) # activate all python versions
- PY_CMD=python3
- $PY_CMD -m pip install --user --upgrade pip wheel setuptools
install:
- $PY_CMD -m pip install --user --upgrade pytest
script:
- |
# Barebones build
cmake -DCMAKE_BUILD_TYPE=Debug -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -DPYTHON_EXECUTABLE=$(which $PY_CMD) .
make pytest -j 2 && make cpptest -j 2
- os: osx
name: Python 2.7, c++14, AppleClang 7.3, CMake test
osx_image: xcode7.3
env: PYTHON=2.7 CPP=14 CLANG CMAKE=1
- os: osx
name: Python 3.7, c++14, AppleClang 9, Debug build
osx_image: xcode9.4
env: PYTHON=3.7 CPP=14 CLANG DEBUG=1
# Test a PyPy 2.7 build
- os: linux
dist: trusty
env: PYPY=5.8 PYTHON=2.7 CPP=11 GCC=4.8
name: PyPy 5.8, Python 2.7, c++11, gcc 4.8
addons:
apt:
packages:
- libblas-dev
- liblapack-dev
- gfortran
# Build in 32-bit mode and tests against the CMake-installed version
- os: linux
dist: trusty
services: docker
env: DOCKER=i386/debian:stretch PYTHON=3.5 CPP=14 GCC=6 INSTALL=1
name: Python 3.5, c++14, gcc 6, 32-bit
script:
- |
# Consolidated 32-bit Docker Build + Install
set -ex
$SCRIPT_RUN_PREFIX sh -c "
set -ex
cmake ${CMAKE_EXTRA_ARGS} -DPYBIND11_INSTALL=1 -DPYBIND11_TEST=0 .
make install
cp -a tests /pybind11-tests
mkdir /build-tests && cd /build-tests
cmake ../pybind11-tests ${CMAKE_EXTRA_ARGS} -DPYBIND11_WERROR=ON
make pytest -j 2"
set +ex
cache:
directories:
- $HOME/.local/bin
- $HOME/.local/lib
- $HOME/.local/include
- $HOME/Library/Python
before_install:
- |
# Configure build variables
set -ex
if [ "$TRAVIS_OS_NAME" = "linux" ]; then
if [ -n "$CLANG" ]; then
export CXX=clang++-$CLANG CC=clang-$CLANG
EXTRA_PACKAGES+=" clang-$CLANG llvm-$CLANG-dev"
else
if [ -z "$GCC" ]; then GCC=4.8
else EXTRA_PACKAGES+=" g++-$GCC"
fi
export CXX=g++-$GCC CC=gcc-$GCC
fi
elif [ "$TRAVIS_OS_NAME" = "osx" ]; then
export CXX=clang++ CC=clang;
fi
if [ -n "$CPP" ]; then CPP=-std=c++$CPP; fi
if [ "${PYTHON:0:1}" = "3" ]; then PY=3; fi
if [ -n "$DEBUG" ]; then CMAKE_EXTRA_ARGS+=" -DCMAKE_BUILD_TYPE=Debug"; fi
set +ex
- |
# Initialize environment
set -ex
if [ -n "$DOCKER" ]; then
docker pull $DOCKER
containerid=$(docker run --detach --tty \
--volume="$PWD":/pybind11 --workdir=/pybind11 \
--env="CC=$CC" --env="CXX=$CXX" --env="DEBIAN_FRONTEND=$DEBIAN_FRONTEND" \
--env=GCC_COLORS=\ \
$DOCKER)
SCRIPT_RUN_PREFIX="docker exec --tty $containerid"
$SCRIPT_RUN_PREFIX sh -c 'for s in 0 15; do sleep $s; apt-get update && apt-get -qy dist-upgrade && break; done'
else
if [ "$PYPY" = "5.8" ]; then
curl -fSL https://bitbucket.org/pypy/pypy/downloads/pypy2-v5.8.0-linux64.tar.bz2 | tar xj
PY_CMD=$(echo `pwd`/pypy2-v5.8.0-linux64/bin/pypy)
CMAKE_EXTRA_ARGS+=" -DPYTHON_EXECUTABLE:FILEPATH=$PY_CMD"
else
PY_CMD=python$PYTHON
if [ "$TRAVIS_OS_NAME" = "osx" ]; then
if [ "$PY" = "3" ]; then
brew update && brew unlink python@2 && brew upgrade python
else
curl -fsSL https://bootstrap.pypa.io/get-pip.py | $PY_CMD - --user
fi
fi
fi
if [ "$PY" = 3 ] || [ -n "$PYPY" ]; then
$PY_CMD -m ensurepip --user
fi
$PY_CMD --version
$PY_CMD -m pip install --user --upgrade pip wheel
fi
set +ex
install:
- |
# Install dependencies
set -ex
cmake --version
if [ -n "$DOCKER" ]; then
if [ -n "$DEBUG" ]; then
PY_DEBUG="python$PYTHON-dbg python$PY-scipy-dbg"
CMAKE_EXTRA_ARGS+=" -DPYTHON_EXECUTABLE=/usr/bin/python${PYTHON}dm"
fi
$SCRIPT_RUN_PREFIX sh -c "for s in 0 15; do sleep \$s; \
apt-get -qy --no-install-recommends install \
$PY_DEBUG python$PYTHON-dev python$PY-pytest python$PY-scipy \
libeigen3-dev libboost-dev cmake make ${EXTRA_PACKAGES} && break; done"
else
if [ "$CLANG" = "7" ]; then
export CXXFLAGS="-stdlib=libc++"
fi
export NPY_NUM_BUILD_JOBS=2
echo "Installing pytest, numpy, scipy..."
local PIP_CMD=""
if [ -n $PYPY ]; then
# For expediency, install only versions that are available on the extra index.
travis_wait 30 \
$PY_CMD -m pip install --user --upgrade --extra-index-url https://imaginary.ca/trusty-pypi \
pytest numpy==1.15.4 scipy==1.2.0
else
$PY_CMD -m pip install --user --upgrade pytest numpy scipy
fi
echo "done."
mkdir eigen
curl -fsSL https://bitbucket.org/eigen/eigen/get/3.3.4.tar.bz2 | \
tar --extract -j --directory=eigen --strip-components=1
export CMAKE_INCLUDE_PATH="${CMAKE_INCLUDE_PATH:+$CMAKE_INCLUDE_PATH:}$PWD/eigen"
fi
set +ex
script:
- |
# CMake Configuration
set -ex
$SCRIPT_RUN_PREFIX cmake ${CMAKE_EXTRA_ARGS} \
-DPYBIND11_PYTHON_VERSION=$PYTHON \
-DPYBIND11_CPP_STANDARD=$CPP \
-DPYBIND11_WERROR=${WERROR:-ON} \
-DDOWNLOAD_CATCH=${DOWNLOAD_CATCH:-ON} \
.
set +ex
- |
# pytest
set -ex
$SCRIPT_RUN_PREFIX make pytest -j 2 VERBOSE=1
set +ex
- |
# cpptest
set -ex
$SCRIPT_RUN_PREFIX make cpptest -j 2
set +ex
- |
# CMake Build Interface
set -ex
if [ -n "$CMAKE" ]; then $SCRIPT_RUN_PREFIX make test_cmake_build; fi
set +ex
after_failure: cat tests/test_cmake_build/*.log*
after_script:
- |
# Cleanup (Docker)
set -ex
if [ -n "$DOCKER" ]; then docker stop "$containerid"; docker rm "$containerid"; fi
set +ex
# CMakeLists.txt -- Build system for the pybind11 modules
#
# Copyright (c) 2015 Wenzel Jakob <wenzel@inf.ethz.ch>
#
# All rights reserved. Use of this source code is governed by a
# BSD-style license that can be found in the LICENSE file.
cmake_minimum_required(VERSION 2.8.12)
if (POLICY CMP0048)
# cmake warns if loaded from a min-3.0-required parent dir, so silence the warning:
cmake_policy(SET CMP0048 NEW)
endif()
# CMake versions < 3.4.0 do not support try_compile/pthread checks without C as active language.
if(CMAKE_VERSION VERSION_LESS 3.4.0)
project(pybind11)
else()
project(pybind11 CXX)
endif()
# Check if pybind11 is being used directly or via add_subdirectory
set(PYBIND11_MASTER_PROJECT OFF)
if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
set(PYBIND11_MASTER_PROJECT ON)
endif()
option(PYBIND11_INSTALL "Install pybind11 header files?" ${PYBIND11_MASTER_PROJECT})
option(PYBIND11_TEST "Build pybind11 test suite?" ${PYBIND11_MASTER_PROJECT})
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/tools")
include(pybind11Tools)
# Cache variables so pybind11_add_module can be used in parent projects
set(PYBIND11_INCLUDE_DIR "${CMAKE_CURRENT_LIST_DIR}/include" CACHE INTERNAL "")
set(PYTHON_INCLUDE_DIRS ${PYTHON_INCLUDE_DIRS} CACHE INTERNAL "")
set(PYTHON_LIBRARIES ${PYTHON_LIBRARIES} CACHE INTERNAL "")
set(PYTHON_MODULE_PREFIX ${PYTHON_MODULE_PREFIX} CACHE INTERNAL "")
set(PYTHON_MODULE_EXTENSION ${PYTHON_MODULE_EXTENSION} CACHE INTERNAL "")
set(PYTHON_VERSION_MAJOR ${PYTHON_VERSION_MAJOR} CACHE INTERNAL "")
set(PYTHON_VERSION_MINOR ${PYTHON_VERSION_MINOR} CACHE INTERNAL "")
# NB: when adding a header don't forget to also add it to setup.py
set(PYBIND11_HEADERS
include/pybind11/detail/class.h
include/pybind11/detail/common.h
include/pybind11/detail/descr.h
include/pybind11/detail/init.h
include/pybind11/detail/internals.h
include/pybind11/detail/typeid.h
include/pybind11/attr.h
include/pybind11/buffer_info.h
include/pybind11/cast.h
include/pybind11/chrono.h
include/pybind11/common.h
include/pybind11/complex.h
include/pybind11/options.h
include/pybind11/eigen.h
include/pybind11/embed.h
include/pybind11/eval.h
include/pybind11/functional.h
include/pybind11/numpy.h
include/pybind11/operators.h
include/pybind11/pybind11.h
include/pybind11/pytypes.h
include/pybind11/stl.h
include/pybind11/stl_bind.h
)
string(REPLACE "include/" "${CMAKE_CURRENT_SOURCE_DIR}/include/"
PYBIND11_HEADERS "${PYBIND11_HEADERS}")
if (PYBIND11_TEST)
add_subdirectory(tests)
endif()
include(GNUInstallDirs)
include(CMakePackageConfigHelpers)
# extract project version from source
file(STRINGS "${PYBIND11_INCLUDE_DIR}/pybind11/detail/common.h" pybind11_version_defines
REGEX "#define PYBIND11_VERSION_(MAJOR|MINOR|PATCH) ")
foreach(ver ${pybind11_version_defines})
if (ver MATCHES "#define PYBIND11_VERSION_(MAJOR|MINOR|PATCH) +([^ ]+)$")
set(PYBIND11_VERSION_${CMAKE_MATCH_1} "${CMAKE_MATCH_2}" CACHE INTERNAL "")
endif()
endforeach()
set(${PROJECT_NAME}_VERSION ${PYBIND11_VERSION_MAJOR}.${PYBIND11_VERSION_MINOR}.${PYBIND11_VERSION_PATCH})
message(STATUS "pybind11 v${${PROJECT_NAME}_VERSION}")
option (USE_PYTHON_INCLUDE_DIR "Install pybind11 headers in Python include directory instead of default installation prefix" OFF)
if (USE_PYTHON_INCLUDE_DIR)
file(RELATIVE_PATH CMAKE_INSTALL_INCLUDEDIR ${CMAKE_INSTALL_PREFIX} ${PYTHON_INCLUDE_DIRS})
endif()
if(NOT (CMAKE_VERSION VERSION_LESS 3.0)) # CMake >= 3.0
# Build an interface library target:
add_library(pybind11 INTERFACE)
add_library(pybind11::pybind11 ALIAS pybind11) # to match exported target
target_include_directories(pybind11 INTERFACE $<BUILD_INTERFACE:${PYBIND11_INCLUDE_DIR}>
$<BUILD_INTERFACE:${PYTHON_INCLUDE_DIRS}>
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
target_compile_options(pybind11 INTERFACE $<BUILD_INTERFACE:${PYBIND11_CPP_STANDARD}>)
add_library(module INTERFACE)
add_library(pybind11::module ALIAS module)
if(NOT MSVC)
target_compile_options(module INTERFACE -fvisibility=hidden)
endif()
target_link_libraries(module INTERFACE pybind11::pybind11)
if(WIN32 OR CYGWIN)
target_link_libraries(module INTERFACE $<BUILD_INTERFACE:${PYTHON_LIBRARIES}>)
elseif(APPLE)
target_link_libraries(module INTERFACE "-undefined dynamic_lookup")
endif()
add_library(embed INTERFACE)
add_library(pybind11::embed ALIAS embed)
target_link_libraries(embed INTERFACE pybind11::pybind11 $<BUILD_INTERFACE:${PYTHON_LIBRARIES}>)
endif()
if (PYBIND11_INSTALL)
install(DIRECTORY ${PYBIND11_INCLUDE_DIR}/pybind11 DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
# GNUInstallDirs "DATADIR" wrong here; CMake search path wants "share".
set(PYBIND11_CMAKECONFIG_INSTALL_DIR "share/cmake/${PROJECT_NAME}" CACHE STRING "install path for pybind11Config.cmake")
configure_package_config_file(tools/${PROJECT_NAME}Config.cmake.in
"${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
INSTALL_DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
# Remove CMAKE_SIZEOF_VOID_P from ConfigVersion.cmake since the library does
# not depend on architecture specific settings or libraries.
set(_PYBIND11_CMAKE_SIZEOF_VOID_P ${CMAKE_SIZEOF_VOID_P})
unset(CMAKE_SIZEOF_VOID_P)
write_basic_package_version_file(${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
VERSION ${${PROJECT_NAME}_VERSION}
COMPATIBILITY AnyNewerVersion)
set(CMAKE_SIZEOF_VOID_P ${_PYBIND11_CMAKE_SIZEOF_VOID_P})
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.cmake
${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake
tools/FindPythonLibsNew.cmake
tools/pybind11Tools.cmake
DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
if(NOT (CMAKE_VERSION VERSION_LESS 3.0))
if(NOT PYBIND11_EXPORT_NAME)
set(PYBIND11_EXPORT_NAME "${PROJECT_NAME}Targets")
endif()
install(TARGETS pybind11 module embed
EXPORT "${PYBIND11_EXPORT_NAME}")
if(PYBIND11_MASTER_PROJECT)
install(EXPORT "${PYBIND11_EXPORT_NAME}"
NAMESPACE "${PROJECT_NAME}::"
DESTINATION ${PYBIND11_CMAKECONFIG_INSTALL_DIR})
endif()
endif()
endif()
Thank you for your interest in this project! Please refer to the following
sections on how to contribute code and bug reports.
### Reporting bugs
At the moment, this project is run in the spare time of a single person
([Wenzel Jakob](http://rgl.epfl.ch/people/wjakob)) with very limited resources
for issue tracker tickets. Thus, before submitting a question or bug report,
please take a moment of your time and ensure that your issue isn't already
discussed in the project documentation provided at
[http://pybind11.readthedocs.org/en/latest](http://pybind11.readthedocs.org/en/latest).
Assuming that you have identified a previously unknown problem or an important
question, it's essential that you submit a self-contained and minimal piece of
code that reproduces the problem. In other words: no external dependencies,
isolate the function(s) that cause breakage, submit matched and complete C++
and Python snippets that can be easily compiled and run on my end.
## Pull requests
Contributions are submitted, reviewed, and accepted using Github pull requests.
Please refer to [this
article](https://help.github.com/articles/using-pull-requests) for details and
adhere to the following rules to make the process as smooth as possible:
* Make a new branch for every feature you're working on.
* Make small and clean pull requests that are easy to review but make sure they
do add value by themselves.
* Add tests for any new functionality and run the test suite (``make pytest``)
to ensure that no existing features break.
* Please run ``flake8`` and ``tools/check-style.sh`` to check your code matches
the project style. (Note that ``check-style.sh`` requires ``gawk``.)
* This project has a strong focus on providing general solutions using a
minimal amount of code, thus small pull requests are greatly preferred.
### Licensing of contributions
pybind11 is provided under a BSD-style license that can be found in the
``LICENSE`` file. By using, distributing, or contributing to this project, you
agree to the terms and conditions of this license.
You are under no obligation whatsoever to provide any bug fixes, patches, or
upgrades to the features, functionality or performance of the source code
("Enhancements") to anyone; however, if you choose to make your Enhancements
available either publicly, or directly to the author of this software, without
imposing a separate written license agreement for such Enhancements, then you
hereby grant the following license: a non-exclusive, royalty-free perpetual
license to install, use, modify, prepare derivative works, incorporate into
other computer software, distribute, and sublicense such enhancements or
derivative works thereof, in binary and source code form.
Make sure you've completed the following steps before submitting your issue -- thank you!
1. Check if your question has already been answered in the [FAQ](http://pybind11.readthedocs.io/en/latest/faq.html) section.
2. Make sure you've read the [documentation](http://pybind11.readthedocs.io/en/latest/). Your issue may be addressed there.
3. If those resources didn't help and you only have a short question (not a bug report), consider asking in the [Gitter chat room](https://gitter.im/pybind/Lobby).
4. If you have a genuine bug report or a more complex question which is not answered in the previous items (or not suitable for chat), please fill in the details below.
5. Include a self-contained and minimal piece of code that reproduces the problem. If that's not possible, try to make the description as clear as possible.
*After reading, remove this checklist and the template text in parentheses below.*
## Issue description
(Provide a short description, state the expected behavior and what actually happens.)
## Reproducible example code
(The code should be minimal, have no external dependencies, isolate the function(s) that cause breakage. Submit matched and complete C++ and Python snippets that can be easily compiled and run to diagnose the issue.)
Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>, All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
3. Neither the name of the copyright holder nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Please also refer to the file CONTRIBUTING.md, which clarifies licensing of
external contributions to this project including patches, pull requests, etc.
recursive-include include/pybind11 *.h
include LICENSE README.md CONTRIBUTING.md
![pybind11 logo](https://github.com/pybind/pybind11/raw/master/docs/pybind11-logo.png)
# pybind11 — Seamless operability between C++11 and Python
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**pybind11** is a lightweight header-only library that exposes C++ types in Python
and vice versa, mainly to create Python bindings of existing C++ code. Its
goals and syntax are similar to the excellent
[Boost.Python](http://www.boost.org/doc/libs/1_58_0/libs/python/doc/) library
by David Abrahams: to minimize boilerplate code in traditional extension
modules by inferring type information using compile-time introspection.
The main issue with Boost.Python—and the reason for creating such a similar
project—is Boost. Boost is an enormously large and complex suite of utility
libraries that works with almost every C++ compiler in existence. This
compatibility has its cost: arcane template tricks and workarounds are
necessary to support the oldest and buggiest of compiler specimens. Now that
C++11-compatible compilers are widely available, this heavy machinery has
become an excessively large and unnecessary dependency.
Think of this library as a tiny self-contained version of Boost.Python with
everything stripped away that isn't relevant for binding generation. Without
comments, the core header files only require ~4K lines of code and depend on
Python (2.7 or 3.x, or PyPy2.7 >= 5.7) and the C++ standard library. This
compact implementation was possible thanks to some of the new C++11 language
features (specifically: tuples, lambda functions and variadic templates). Since
its creation, this library has grown beyond Boost.Python in many ways, leading
to dramatically simpler binding code in many common situations.
Tutorial and reference documentation is provided at
[http://pybind11.readthedocs.org/en/master](http://pybind11.readthedocs.org/en/master).
A PDF version of the manual is available
[here](https://media.readthedocs.org/pdf/pybind11/master/pybind11.pdf).
## Core features
pybind11 can map the following core C++ features to Python
- Functions accepting and returning custom data structures per value, reference, or pointer
- Instance methods and static methods
- Overloaded functions
- Instance attributes and static attributes
- Arbitrary exception types
- Enumerations
- Callbacks
- Iterators and ranges
- Custom operators
- Single and multiple inheritance
- STL data structures
- Smart pointers with reference counting like ``std::shared_ptr``
- Internal references with correct reference counting
- C++ classes with virtual (and pure virtual) methods can be extended in Python
## Goodies
In addition to the core functionality, pybind11 provides some extra goodies:
- Python 2.7, 3.x, and PyPy (PyPy2.7 >= 5.7) are supported with an
implementation-agnostic interface.
- It is possible to bind C++11 lambda functions with captured variables. The
lambda capture data is stored inside the resulting Python function object.
- pybind11 uses C++11 move constructors and move assignment operators whenever
possible to efficiently transfer custom data types.
- It's easy to expose the internal storage of custom data types through
Pythons' buffer protocols. This is handy e.g. for fast conversion between
C++ matrix classes like Eigen and NumPy without expensive copy operations.
- pybind11 can automatically vectorize functions so that they are transparently
applied to all entries of one or more NumPy array arguments.
- Python's slice-based access and assignment operations can be supported with
just a few lines of code.
- Everything is contained in just a few header files; there is no need to link
against any additional libraries.
- Binaries are generally smaller by a factor of at least 2 compared to
equivalent bindings generated by Boost.Python. A recent pybind11 conversion
of PyRosetta, an enormous Boost.Python binding project,
[reported](http://graylab.jhu.edu/RosettaCon2016/PyRosetta-4.pdf) a binary
size reduction of **5.4x** and compile time reduction by **5.8x**.
- Function signatures are precomputed at compile time (using ``constexpr``),
leading to smaller binaries.
- With little extra effort, C++ types can be pickled and unpickled similar to
regular Python objects.
## Supported compilers
1. Clang/LLVM 3.3 or newer (for Apple Xcode's clang, this is 5.0.0 or newer)
2. GCC 4.8 or newer
3. Microsoft Visual Studio 2015 Update 3 or newer
4. Intel C++ compiler 17 or newer (16 with pybind11 v2.0 and 15 with pybind11 v2.0 and a [workaround](https://github.com/pybind/pybind11/issues/276))
5. Cygwin/GCC (tested on 2.5.1)
## About
This project was created by [Wenzel Jakob](http://rgl.epfl.ch/people/wjakob).
Significant features and/or improvements to the code were contributed by
Jonas Adler,
Lori A. Burns,
Sylvain Corlay,
Trent Houliston,
Axel Huebl,
@hulucc,
Sergey Lyskov
Johan Mabille,
Tomasz Miąsko,
Dean Moldovan,
Ben Pritchard,
Jason Rhinelander,
Boris Schäling,
Pim Schellart,
Henry Schreiner,
Ivan Smirnov, and
Patrick Stewart.
### License
pybind11 is provided under a BSD-style license that can be found in the
``LICENSE`` file. By using, distributing, or contributing to this project,
you agree to the terms and conditions of this license.
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Chrono
======
When including the additional header file :file:`pybind11/chrono.h` conversions
from C++11 chrono datatypes to python datetime objects are automatically enabled.
This header also enables conversions of python floats (often from sources such
as ``time.monotonic()``, ``time.perf_counter()`` and ``time.process_time()``)
into durations.
An overview of clocks in C++11
------------------------------
A point of confusion when using these conversions is the differences between
clocks provided in C++11. There are three clock types defined by the C++11
standard and users can define their own if needed. Each of these clocks have
different properties and when converting to and from python will give different
results.
The first clock defined by the standard is ``std::chrono::system_clock``. This
clock measures the current date and time. However, this clock changes with to
updates to the operating system time. For example, if your time is synchronised
with a time server this clock will change. This makes this clock a poor choice
for timing purposes but good for measuring the wall time.
The second clock defined in the standard is ``std::chrono::steady_clock``.
This clock ticks at a steady rate and is never adjusted. This makes it excellent
for timing purposes, however the value in this clock does not correspond to the
current date and time. Often this clock will be the amount of time your system
has been on, although it does not have to be. This clock will never be the same
clock as the system clock as the system clock can change but steady clocks
cannot.
The third clock defined in the standard is ``std::chrono::high_resolution_clock``.
This clock is the clock that has the highest resolution out of the clocks in the
system. It is normally a typedef to either the system clock or the steady clock
but can be its own independent clock. This is important as when using these
conversions as the types you get in python for this clock might be different
depending on the system.
If it is a typedef of the system clock, python will get datetime objects, but if
it is a different clock they will be timedelta objects.
Provided conversions
--------------------
.. rubric:: C++ to Python
- ``std::chrono::system_clock::time_point`` → ``datetime.datetime``
System clock times are converted to python datetime instances. They are
in the local timezone, but do not have any timezone information attached
to them (they are naive datetime objects).
- ``std::chrono::duration`` → ``datetime.timedelta``
Durations are converted to timedeltas, any precision in the duration
greater than microseconds is lost by rounding towards zero.
- ``std::chrono::[other_clocks]::time_point`` → ``datetime.timedelta``
Any clock time that is not the system clock is converted to a time delta.
This timedelta measures the time from the clocks epoch to now.
.. rubric:: Python to C++
- ``datetime.datetime`` or ``datetime.date`` or ``datetime.time`` → ``std::chrono::system_clock::time_point``
Date/time objects are converted into system clock timepoints. Any
timezone information is ignored and the type is treated as a naive
object.
- ``datetime.timedelta`` → ``std::chrono::duration``
Time delta are converted into durations with microsecond precision.
- ``datetime.timedelta`` → ``std::chrono::[other_clocks]::time_point``
Time deltas that are converted into clock timepoints are treated as
the amount of time from the start of the clocks epoch.
- ``float`` → ``std::chrono::duration``
Floats that are passed to C++ as durations be interpreted as a number of
seconds. These will be converted to the duration using ``duration_cast``
from the float.
- ``float`` → ``std::chrono::[other_clocks]::time_point``
Floats that are passed to C++ as time points will be interpreted as the
number of seconds from the start of the clocks epoch.
Custom type casters
===================
In very rare cases, applications may require custom type casters that cannot be
expressed using the abstractions provided by pybind11, thus requiring raw
Python C API calls. This is fairly advanced usage and should only be pursued by
experts who are familiar with the intricacies of Python reference counting.
The following snippets demonstrate how this works for a very simple ``inty``
type that that should be convertible from Python types that provide a
``__int__(self)`` method.
.. code-block:: cpp
struct inty { long long_value; };
void print(inty s) {
std::cout << s.long_value << std::endl;
}
The following Python snippet demonstrates the intended usage from the Python side:
.. code-block:: python
class A:
def __int__(self):
return 123
from example import print
print(A())
To register the necessary conversion routines, it is necessary to add
a partial overload to the ``pybind11::detail::type_caster<T>`` template.
Although this is an implementation detail, adding partial overloads to this
type is explicitly allowed.
.. code-block:: cpp
namespace pybind11 { namespace detail {
template <> struct type_caster<inty> {
public:
/**
* This macro establishes the name 'inty' in
* function signatures and declares a local variable
* 'value' of type inty
*/
PYBIND11_TYPE_CASTER(inty, _("inty"));
/**
* Conversion part 1 (Python->C++): convert a PyObject into a inty
* instance or return false upon failure. The second argument
* indicates whether implicit conversions should be applied.
*/
bool load(handle src, bool) {
/* Extract PyObject from handle */
PyObject *source = src.ptr();
/* Try converting into a Python integer value */
PyObject *tmp = PyNumber_Long(source);
if (!tmp)
return false;
/* Now try to convert into a C++ int */
value.long_value = PyLong_AsLong(tmp);
Py_DECREF(tmp);
/* Ensure return code was OK (to avoid out-of-range errors etc) */
return !(value.long_value == -1 && !PyErr_Occurred());
}
/**
* Conversion part 2 (C++ -> Python): convert an inty instance into
* a Python object. The second and third arguments are used to
* indicate the return value policy and parent object (for
* ``return_value_policy::reference_internal``) and are generally
* ignored by implicit casters.
*/
static handle cast(inty src, return_value_policy /* policy */, handle /* parent */) {
return PyLong_FromLong(src.long_value);
}
};
}} // namespace pybind11::detail
.. note::
A ``type_caster<T>`` defined with ``PYBIND11_TYPE_CASTER(T, ...)`` requires
that ``T`` is default-constructible (``value`` is first default constructed
and then ``load()`` assigns to it).
.. warning::
When using custom type casters, it's important to declare them consistently
in every compilation unit of the Python extension module. Otherwise,
undefined behavior can ensue.
Eigen
#####
`Eigen <http://eigen.tuxfamily.org>`_ is C++ header-based library for dense and
sparse linear algebra. Due to its popularity and widespread adoption, pybind11
provides transparent conversion and limited mapping support between Eigen and
Scientific Python linear algebra data types.
To enable the built-in Eigen support you must include the optional header file
:file:`pybind11/eigen.h`.
Pass-by-value
=============
When binding a function with ordinary Eigen dense object arguments (for
example, ``Eigen::MatrixXd``), pybind11 will accept any input value that is
already (or convertible to) a ``numpy.ndarray`` with dimensions compatible with
the Eigen type, copy its values into a temporary Eigen variable of the
appropriate type, then call the function with this temporary variable.
Sparse matrices are similarly copied to or from
``scipy.sparse.csr_matrix``/``scipy.sparse.csc_matrix`` objects.
Pass-by-reference
=================
One major limitation of the above is that every data conversion implicitly
involves a copy, which can be both expensive (for large matrices) and disallows
binding functions that change their (Matrix) arguments. Pybind11 allows you to
work around this by using Eigen's ``Eigen::Ref<MatrixType>`` class much as you
would when writing a function taking a generic type in Eigen itself (subject to
some limitations discussed below).
When calling a bound function accepting a ``Eigen::Ref<const MatrixType>``
type, pybind11 will attempt to avoid copying by using an ``Eigen::Map`` object
that maps into the source ``numpy.ndarray`` data: this requires both that the
data types are the same (e.g. ``dtype='float64'`` and ``MatrixType::Scalar`` is
``double``); and that the storage is layout compatible. The latter limitation
is discussed in detail in the section below, and requires careful
consideration: by default, numpy matrices and Eigen matrices are *not* storage
compatible.
If the numpy matrix cannot be used as is (either because its types differ, e.g.
passing an array of integers to an Eigen parameter requiring doubles, or
because the storage is incompatible), pybind11 makes a temporary copy and
passes the copy instead.
When a bound function parameter is instead ``Eigen::Ref<MatrixType>`` (note the
lack of ``const``), pybind11 will only allow the function to be called if it
can be mapped *and* if the numpy array is writeable (that is
``a.flags.writeable`` is true). Any access (including modification) made to
the passed variable will be transparently carried out directly on the
``numpy.ndarray``.
This means you can can write code such as the following and have it work as
expected:
.. code-block:: cpp
void scale_by_2(Eigen::Ref<Eigen::VectorXd> v) {
v *= 2;
}
Note, however, that you will likely run into limitations due to numpy and
Eigen's difference default storage order for data; see the below section on
:ref:`storage_orders` for details on how to bind code that won't run into such
limitations.
.. note::
Passing by reference is not supported for sparse types.
Returning values to Python
==========================
When returning an ordinary dense Eigen matrix type to numpy (e.g.
``Eigen::MatrixXd`` or ``Eigen::RowVectorXf``) pybind11 keeps the matrix and
returns a numpy array that directly references the Eigen matrix: no copy of the
data is performed. The numpy array will have ``array.flags.owndata`` set to
``False`` to indicate that it does not own the data, and the lifetime of the
stored Eigen matrix will be tied to the returned ``array``.
If you bind a function with a non-reference, ``const`` return type (e.g.
``const Eigen::MatrixXd``), the same thing happens except that pybind11 also
sets the numpy array's ``writeable`` flag to false.
If you return an lvalue reference or pointer, the usual pybind11 rules apply,
as dictated by the binding function's return value policy (see the
documentation on :ref:`return_value_policies` for full details). That means,
without an explicit return value policy, lvalue references will be copied and
pointers will be managed by pybind11. In order to avoid copying, you should
explicitly specify an appropriate return value policy, as in the following
example:
.. code-block:: cpp
class MyClass {
Eigen::MatrixXd big_mat = Eigen::MatrixXd::Zero(10000, 10000);
public:
Eigen::MatrixXd &getMatrix() { return big_mat; }
const Eigen::MatrixXd &viewMatrix() { return big_mat; }
};
// Later, in binding code:
py::class_<MyClass>(m, "MyClass")
.def(py::init<>())
.def("copy_matrix", &MyClass::getMatrix) // Makes a copy!
.def("get_matrix", &MyClass::getMatrix, py::return_value_policy::reference_internal)
.def("view_matrix", &MyClass::viewMatrix, py::return_value_policy::reference_internal)
;
.. code-block:: python
a = MyClass()
m = a.get_matrix() # flags.writeable = True, flags.owndata = False
v = a.view_matrix() # flags.writeable = False, flags.owndata = False
c = a.copy_matrix() # flags.writeable = True, flags.owndata = True
# m[5,6] and v[5,6] refer to the same element, c[5,6] does not.
Note in this example that ``py::return_value_policy::reference_internal`` is
used to tie the life of the MyClass object to the life of the returned arrays.
You may also return an ``Eigen::Ref``, ``Eigen::Map`` or other map-like Eigen
object (for example, the return value of ``matrix.block()`` and related
methods) that map into a dense Eigen type. When doing so, the default
behaviour of pybind11 is to simply reference the returned data: you must take
care to ensure that this data remains valid! You may ask pybind11 to
explicitly *copy* such a return value by using the
``py::return_value_policy::copy`` policy when binding the function. You may
also use ``py::return_value_policy::reference_internal`` or a
``py::keep_alive`` to ensure the data stays valid as long as the returned numpy
array does.
When returning such a reference of map, pybind11 additionally respects the
readonly-status of the returned value, marking the numpy array as non-writeable
if the reference or map was itself read-only.
.. note::
Sparse types are always copied when returned.
.. _storage_orders:
Storage orders
==============
Passing arguments via ``Eigen::Ref`` has some limitations that you must be
aware of in order to effectively pass matrices by reference. First and
foremost is that the default ``Eigen::Ref<MatrixType>`` class requires
contiguous storage along columns (for column-major types, the default in Eigen)
or rows if ``MatrixType`` is specifically an ``Eigen::RowMajor`` storage type.
The former, Eigen's default, is incompatible with ``numpy``'s default row-major
storage, and so you will not be able to pass numpy arrays to Eigen by reference
without making one of two changes.
(Note that this does not apply to vectors (or column or row matrices): for such
types the "row-major" and "column-major" distinction is meaningless).
The first approach is to change the use of ``Eigen::Ref<MatrixType>`` to the
more general ``Eigen::Ref<MatrixType, 0, Eigen::Stride<Eigen::Dynamic,
Eigen::Dynamic>>`` (or similar type with a fully dynamic stride type in the
third template argument). Since this is a rather cumbersome type, pybind11
provides a ``py::EigenDRef<MatrixType>`` type alias for your convenience (along
with EigenDMap for the equivalent Map, and EigenDStride for just the stride
type).
This type allows Eigen to map into any arbitrary storage order. This is not
the default in Eigen for performance reasons: contiguous storage allows
vectorization that cannot be done when storage is not known to be contiguous at
compile time. The default ``Eigen::Ref`` stride type allows non-contiguous
storage along the outer dimension (that is, the rows of a column-major matrix
or columns of a row-major matrix), but not along the inner dimension.
This type, however, has the added benefit of also being able to map numpy array
slices. For example, the following (contrived) example uses Eigen with a numpy
slice to multiply by 2 all coefficients that are both on even rows (0, 2, 4,
...) and in columns 2, 5, or 8:
.. code-block:: cpp
m.def("scale", [](py::EigenDRef<Eigen::MatrixXd> m, double c) { m *= c; });
.. code-block:: python
# a = np.array(...)
scale_by_2(myarray[0::2, 2:9:3])
The second approach to avoid copying is more intrusive: rearranging the
underlying data types to not run into the non-contiguous storage problem in the
first place. In particular, that means using matrices with ``Eigen::RowMajor``
storage, where appropriate, such as:
.. code-block:: cpp
using RowMatrixXd = Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor>;
// Use RowMatrixXd instead of MatrixXd
Now bound functions accepting ``Eigen::Ref<RowMatrixXd>`` arguments will be
callable with numpy's (default) arrays without involving a copying.
You can, alternatively, change the storage order that numpy arrays use by
adding the ``order='F'`` option when creating an array:
.. code-block:: python
myarray = np.array(source, order='F')
Such an object will be passable to a bound function accepting an
``Eigen::Ref<MatrixXd>`` (or similar column-major Eigen type).
One major caveat with this approach, however, is that it is not entirely as
easy as simply flipping all Eigen or numpy usage from one to the other: some
operations may alter the storage order of a numpy array. For example, ``a2 =
array.transpose()`` results in ``a2`` being a view of ``array`` that references
the same data, but in the opposite storage order!
While this approach allows fully optimized vectorized calculations in Eigen, it
cannot be used with array slices, unlike the first approach.
When *returning* a matrix to Python (either a regular matrix, a reference via
``Eigen::Ref<>``, or a map/block into a matrix), no special storage
consideration is required: the created numpy array will have the required
stride that allows numpy to properly interpret the array, whatever its storage
order.
Failing rather than copying
===========================
The default behaviour when binding ``Eigen::Ref<const MatrixType>`` Eigen
references is to copy matrix values when passed a numpy array that does not
conform to the element type of ``MatrixType`` or does not have a compatible
stride layout. If you want to explicitly avoid copying in such a case, you
should bind arguments using the ``py::arg().noconvert()`` annotation (as
described in the :ref:`nonconverting_arguments` documentation).
The following example shows an example of arguments that don't allow data
copying to take place:
.. code-block:: cpp
// The method and function to be bound:
class MyClass {
// ...
double some_method(const Eigen::Ref<const MatrixXd> &matrix) { /* ... */ }
};
float some_function(const Eigen::Ref<const MatrixXf> &big,
const Eigen::Ref<const MatrixXf> &small) {
// ...
}
// The associated binding code:
using namespace pybind11::literals; // for "arg"_a
py::class_<MyClass>(m, "MyClass")
// ... other class definitions
.def("some_method", &MyClass::some_method, py::arg().noconvert());
m.def("some_function", &some_function,
"big"_a.noconvert(), // <- Don't allow copying for this arg
"small"_a // <- This one can be copied if needed
);
With the above binding code, attempting to call the the ``some_method(m)``
method on a ``MyClass`` object, or attempting to call ``some_function(m, m2)``
will raise a ``RuntimeError`` rather than making a temporary copy of the array.
It will, however, allow the ``m2`` argument to be copied into a temporary if
necessary.
Note that explicitly specifying ``.noconvert()`` is not required for *mutable*
Eigen references (e.g. ``Eigen::Ref<MatrixXd>`` without ``const`` on the
``MatrixXd``): mutable references will never be called with a temporary copy.
Vectors versus column/row matrices
==================================
Eigen and numpy have fundamentally different notions of a vector. In Eigen, a
vector is simply a matrix with the number of columns or rows set to 1 at
compile time (for a column vector or row vector, respectively). Numpy, in
contrast, has comparable 2-dimensional 1xN and Nx1 arrays, but *also* has
1-dimensional arrays of size N.
When passing a 2-dimensional 1xN or Nx1 array to Eigen, the Eigen type must
have matching dimensions: That is, you cannot pass a 2-dimensional Nx1 numpy
array to an Eigen value expecting a row vector, or a 1xN numpy array as a
column vector argument.
On the other hand, pybind11 allows you to pass 1-dimensional arrays of length N
as Eigen parameters. If the Eigen type can hold a column vector of length N it
will be passed as such a column vector. If not, but the Eigen type constraints
will accept a row vector, it will be passed as a row vector. (The column
vector takes precedence when both are supported, for example, when passing a
1D numpy array to a MatrixXd argument). Note that the type need not be
explicitly a vector: it is permitted to pass a 1D numpy array of size 5 to an
Eigen ``Matrix<double, Dynamic, 5>``: you would end up with a 1x5 Eigen matrix.
Passing the same to an ``Eigen::MatrixXd`` would result in a 5x1 Eigen matrix.
When returning an Eigen vector to numpy, the conversion is ambiguous: a row
vector of length 4 could be returned as either a 1D array of length 4, or as a
2D array of size 1x4. When encountering such a situation, pybind11 compromises
by considering the returned Eigen type: if it is a compile-time vector--that
is, the type has either the number of rows or columns set to 1 at compile
time--pybind11 converts to a 1D numpy array when returning the value. For
instances that are a vector only at run-time (e.g. ``MatrixXd``,
``Matrix<float, Dynamic, 4>``), pybind11 returns the vector as a 2D array to
numpy. If this isn't want you want, you can use ``array.reshape(...)`` to get
a view of the same data in the desired dimensions.
.. seealso::
The file :file:`tests/test_eigen.cpp` contains a complete example that
shows how to pass Eigen sparse and dense data types in more detail.
Functional
##########
The following features must be enabled by including :file:`pybind11/functional.h`.
Callbacks and passing anonymous functions
=========================================
The C++11 standard brought lambda functions and the generic polymorphic
function wrapper ``std::function<>`` to the C++ programming language, which
enable powerful new ways of working with functions. Lambda functions come in
two flavors: stateless lambda function resemble classic function pointers that
link to an anonymous piece of code, while stateful lambda functions
additionally depend on captured variables that are stored in an anonymous
*lambda closure object*.
Here is a simple example of a C++ function that takes an arbitrary function
(stateful or stateless) with signature ``int -> int`` as an argument and runs
it with the value 10.
.. code-block:: cpp
int func_arg(const std::function<int(int)> &f) {
return f(10);
}
The example below is more involved: it takes a function of signature ``int -> int``
and returns another function of the same kind. The return value is a stateful
lambda function, which stores the value ``f`` in the capture object and adds 1 to
its return value upon execution.
.. code-block:: cpp
std::function<int(int)> func_ret(const std::function<int(int)> &f) {
return [f](int i) {
return f(i) + 1;
};
}
This example demonstrates using python named parameters in C++ callbacks which
requires using ``py::cpp_function`` as a wrapper. Usage is similar to defining
methods of classes:
.. code-block:: cpp
py::cpp_function func_cpp() {
return py::cpp_function([](int i) { return i+1; },
py::arg("number"));
}
After including the extra header file :file:`pybind11/functional.h`, it is almost
trivial to generate binding code for all of these functions.
.. code-block:: cpp
#include <pybind11/functional.h>
PYBIND11_MODULE(example, m) {
m.def("func_arg", &func_arg);
m.def("func_ret", &func_ret);
m.def("func_cpp", &func_cpp);
}
The following interactive session shows how to call them from Python.
.. code-block:: pycon
$ python
>>> import example
>>> def square(i):
... return i * i
...
>>> example.func_arg(square)
100L
>>> square_plus_1 = example.func_ret(square)
>>> square_plus_1(4)
17L
>>> plus_1 = func_cpp()
>>> plus_1(number=43)
44L
.. warning::
Keep in mind that passing a function from C++ to Python (or vice versa)
will instantiate a piece of wrapper code that translates function
invocations between the two languages. Naturally, this translation
increases the computational cost of each function call somewhat. A
problematic situation can arise when a function is copied back and forth
between Python and C++ many times in a row, in which case the underlying
wrappers will accumulate correspondingly. The resulting long sequence of
C++ -> Python -> C++ -> ... roundtrips can significantly decrease
performance.
There is one exception: pybind11 detects case where a stateless function
(i.e. a function pointer or a lambda function without captured variables)
is passed as an argument to another C++ function exposed in Python. In this
case, there is no overhead. Pybind11 will extract the underlying C++
function pointer from the wrapped function to sidestep a potential C++ ->
Python -> C++ roundtrip. This is demonstrated in :file:`tests/test_callbacks.cpp`.
.. note::
This functionality is very useful when generating bindings for callbacks in
C++ libraries (e.g. GUI libraries, asynchronous networking libraries, etc.).
The file :file:`tests/test_callbacks.cpp` contains a complete example
that demonstrates how to work with callbacks and anonymous functions in
more detail.
Type conversions
################
Apart from enabling cross-language function calls, a fundamental problem
that a binding tool like pybind11 must address is to provide access to
native Python types in C++ and vice versa. There are three fundamentally
different ways to do this—which approach is preferable for a particular type
depends on the situation at hand.
1. Use a native C++ type everywhere. In this case, the type must be wrapped
using pybind11-generated bindings so that Python can interact with it.
2. Use a native Python type everywhere. It will need to be wrapped so that
C++ functions can interact with it.
3. Use a native C++ type on the C++ side and a native Python type on the
Python side. pybind11 refers to this as a *type conversion*.
Type conversions are the most "natural" option in the sense that native
(non-wrapped) types are used everywhere. The main downside is that a copy
of the data must be made on every Python ↔ C++ transition: this is
needed since the C++ and Python versions of the same type generally won't
have the same memory layout.
pybind11 can perform many kinds of conversions automatically. An overview
is provided in the table ":ref:`conversion_table`".
The following subsections discuss the differences between these options in more
detail. The main focus in this section is on type conversions, which represent
the last case of the above list.
.. toctree::
:maxdepth: 1
overview
strings
stl
functional
chrono
eigen
custom
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